44 AMEBOID MOVEMENT 



ness ; such amebas could be given specific names for reference 

 but they could not be classified in a natural system excepting per- 

 haps as a group. 



But the definiteness and the consistency with which the nuclear 

 division stages occur in any given species of ameba, lends sup- 

 port to the probability that in these animals the relation existing 

 between the chromatin and the cytoplasm are similar to those 

 observed in higher animals ; and that the laws governing the m 

 transmission of cytoplasmic characters in amebas are quite as 

 inflexible as those governing somatoplasmic characters in the 

 higher organisms. Among the investigators of cytologic and 

 genetic phenomena (among the multicellulars) the belief is prac- 

 tically unanimous that the elaborate mechanism involved in nu- 

 clear division is primarily a design for distributing the factors 

 concerned in heredity. Now it would be very strange indeed if 

 a similar and quite as complicated a mechanism in ameba had no 

 function to perform. For what would be the purpose of the 

 complicated nuclear changes in ameba if not concerned with 

 heredity ? As has already been seen, however, there are numerous 

 cytoplasmic characters, in the larger amebas at least, that are in- 

 herited from one generation to the next with as little variation as 

 is observed in other organisms (Schaeffer, '16). The recent 

 work of Jennings ('16) on Difflugia and Hegner ('18) on Arcella 

 also indicates that the general processes of inheritance in these 

 organisms which are closely related to amebas, are similar to 

 those observed in higher forms. The conclusion seems justified 

 therefore that the nuclear changes in amebas mean essentially the 

 same thing as in other organisms. 



We are now therefore in a position to say that amebas are 

 definitely and thoroughly organized ; that they are not really 

 "shapeless"; that they are not more subject to variation than a 

 higher organism is ; and that each species differs from all others 

 in probably every visible detail. The large variety of pseuclopods 

 observed in different species are seen not to be the result of 

 physical or extrinsic chemical forces acting upon ectoplasms dif- 

 fering in some mere physical character as viscosity. But all these 

 peculiarities are hereditary, and are due to a fundamental chemical 

 structure of the protoplasm which is specific for the species. The 



